#define _CRT_SECURE_NO_WARNINGS 1

#include <stdio.h>
#include <string.h>

void my_strcat(char* arr1, const char* arr2)
{
	int i = 0;
	int j = 0;
	while (*(arr1 + i) != '\0')
		i++;
	for (j = 0; *(arr2 + j) != '\0'; i++, j++)
	{
		*(arr1 + i) = *(arr2 + j);
	}
	*(arr1 + i) = '\0';
}

int main()
{
	char arr1[10] = "abc";
	char* arr2 = "def";
	printf("%s\n", arr1);
	my_strcat(arr1, arr2);
	printf("%s\n", arr1);
	return 0;
}